Add DocumentTiming metrics for "time to first text paint"

Source/platform/fonts/FontFallbackList.cpp

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 28 matching lines @@
 namespace blink {
 
 FontFallbackList::FontFallbackList()
     : m_pageZero(0)
     , m_cachedPrimarySimpleFontData(0)
     , m_fontSelector(nullptr)
     , m_fontSelectorVersion(0)
     , m_familyIndex(0)
     , m_generation(FontCache::fontCache()->generation())
     , m_hasLoadingFallback(false)
+    , m_hasCustomFont(false)
 {
 }
 
 void FontFallbackList::invalidate(PassRefPtrWillBeRawPtr<FontSelector> fontSelector)
 {
     releaseFontData();
     m_fontList.clear();
     m_pageZero = 0;
     m_pages.clear();
     m_cachedPrimarySimpleFontData = 0;
     m_familyIndex = 0;
     m_hasLoadingFallback = false;
+    m_hasCustomFont = false;
     if (m_fontSelector != fontSelector)
         m_fontSelector = fontSelector;
     m_fontSelectorVersion = m_fontSelector ? m_fontSelector->version() : 0;
     m_generation = FontCache::fontCache()->generation();
     m_cachingWordShaper.clear();
 }
 
 void FontFallbackList::releaseFontData()
 {
     unsigned numFonts = m_fontList.size();
@@ skipping 133 matching lines @@
     // Ask the font cache for the font data.
     // We are obtaining this font for the first time.  We keep track of the families we've looked at before
     // in |m_familyIndex|, so that we never scan the same spot in the list twice.  getFontData will adjust our
     // |m_familyIndex| as it scans for the right font to make.
     ASSERT(FontCache::fontCache()->generation() == m_generation);
     RefPtr<FontData> result = getFontData(fontDescription, m_familyIndex);
     if (result) {
         m_fontList.append(result);
         if (result->isLoadingFallback())
             m_hasLoadingFallback = true;
+        if (result->isCustomFont())
+            m_hasCustomFont = true;
     }
     return result.get();
 }
 
 bool FontFallbackList::isValid() const
 {
     if (!m_fontSelector)
         return m_fontSelectorVersion == 0;
 
     return m_fontSelector->version() == m_fontSelectorVersion;
 }
 
 } // namespace blink